Utilization of unused disk space on networked computers

ABSTRACT

A plurality of computers in a network each have a processor and a non-volatile data storage device such as a hard disk, a raid array, or the like. Each data storage device is divided into a first data storage area and a second data storage area. The first data storage area is reserved for use by at least one processor to which it is assigned, whereas the second data storage area is hidden from use by the file system of the computer, and is used to store replicated data of other ones of the plurality of computer entities. In the event of failure of any one of the data storage devices, data can be recovered from the second data storage areas of the other data storage devices.

FIELD OF THE INVENTION

The present invention relates to the field of data storage in computers,and particularly, although not exclusively, to a plurality of networkedcomputers storing data on internal non-volatile memory devices.

BACKGROUND TO THE INVENTION

Conventionally, corporations using a plurality of computers, for examplea plurality of networked personal computers (PCs) or Macintosh® typecomputers, make backup copies of data on a networked system to guardagainst loss of data caused by computer or disk drive failure, or byloss of computers or disk drives. There are many known types of back uphardware systems, and conventionally these fall into 3 broad categoriestermed on-line, near-line and off-line backup systems.

On-line backup systems are aimed at backing up data lost due to failureof parts of computer networks, where the backup procedure can beinitiated almost immediately, once the loss of data is discovered.On-line backup systems form an integral part of a computer network, andincludes such systems as a redundant server which mirrors the data in amain server, and which is connected over a same local area network asthe main server. On-line systems, particularly for small companies, donot protect against catastrophic events such as a fire destroying allthe computer equipment, or theft of all computer equipment in a network.However, they provide relatively fast recovery times from equipmentfailure.

Near-line systems involve storage of data on devices having lowerresponse times than on-line systems in the event of data loss.Typically, a near-line system may comprise a CD ROM cassette system, ora tape-spool system, where the CD ROMs and tapes are removable from adrive. Large volumes of CD ROMs or tapes may be stored within a samebuilding as the computer network, and which are readily available in theevent of data loss.

Off-line systems include backup to data storage devices which areremoved from the physical location of the network, for example stored afew miles away. In the event of a catastrophic failure of the network,e.g. theft of all computers, or destruction of all computers by fire,off-line systems provide the means to recover data. Off-line systemstypically have delay times in restoring backup data which are greaterthan near-line systems.

There are a wide variety of legacy backup systems in use, however manycorporations run computer networks which, in practice, have shortfallsin backup procedures and which leave companies vulnerable to loss ofdata. Many corporations are without on-line, near-line or off-linebackup facilities, or have gaps in their backup coverage having onlyon-line or off-line and no near-line facilities, or on-line facilitiesonly with no off-line facilities for example.

In the PC market, recently the data capacity of disk drives sold withinPCs has increased to levels at which many users have large volumes ofspare non-volatile memory available, which exceeds their local PC datastorage requirements. For example, in a system of networked personalcomputers running on a Unix or Windows NT® operating system, andcommunicating with the file server upon which data is stored, individualPCs may have unused non-volatile data storage capacities in the range1-9 gigabytes per PC. This effectively represents a computer resourcewhich has been paid for, but which remains unused. Whatever the size ofcomputer network, having unused non-volatile disk space in a networkadds to the cost of ownership of a network, but provides no benefit tothe network owner.

EP 0854423 teaches of a method for distributed data processing usingindividual platforms interconnected by a communication network. Theindividual platforms are configured to process, control and store datain a distributed manner. In the event of a failure of a particularplatform, the remaining interconnected platforms, having shared data ofthe failed platform distributed across their network, process the tasksof this failed platform.

A similar distributed data processing network is found in WO 96/37837which teaches of a computer system potentially capable of dataself-repair in the event of multiple individual platform failures. Thisdisclosure is directed to fault tolerance in a database server system.

U.S. Pat. No. 5,586,310 is further concerned with distributed dataprocessing and is directed to provide a distributed processing systemconfigured to update global distributed data following a local dataupdate at an individual platform. The disclosure is of a distributeddatabase technology, having take-over of one node's data, which resideselsewhere, upon failure of the originating node.

With reference, in part, to the prior art the inventors have recognisedthe need for distributed data storage utilizing spare non-volatile diskstorage devices, these devices being non-localised thereby forming adistributed storage capacity. In particular, the inventors recognise aneed for a management utility forming part of the distributed datastorage system, whereby the management utility is capable of performinga variety of functions. In particular, the setting up of the distributeddata network, the selecting of individual computer entities toparticipate in the network, and the sizing and dividing of individualnon-volatile data storage devices in order to optimise data storage andrecovery. Such a management utility not being found in the art.

The inventors have recognized that spare non-volatile disk storagecapacity on individual computers in a network represents an unusedresource which by putting the unused disk space to use in providing adata backup facility can be used to reduce the overall cost of ownershipof a network and reduce the cost of ownership of each unit of computingcapability provided by a network.

SUMMARY OF THE INVENTION

One object of the present invention is to utilize unused non-volatiledata storage space on individual computers in a network of computers,for the purpose of data protection. For any individual computer, anon-volatile memory storage device, such as hard disk drive, is dividedinto a first area, which is available for use by the computer forstorage of applications, user data, executable files and the like, and asecond data storage area which is useable for storing backup data of oneor more user data areas of a plurality of other non-volatile memorydevices in a plurality of other computers in a network.

In the majority of prior art computer networks comprising a plurality ofprior art computer entities, there exists unused non-volatile datastorage area on hard disk drives which will never be used. Thisrepresents a resource which has been paid for by a customer, but whichgives no benefit to the user. Specific implementations of the presentinvention aim to put this unused resource, which has to be paid forwhether used or not, to better use in enabling a fast on-line datarecovery in the event of corruption of data on at least one of thenon-volatile data storage devices in a computer network. Implementationof the invention may provide a distributed data storage and recoverynetwork having a systems manager utility which allows a user to searchand select individual computer platforms to participate in the assembledglobal distributed data system. The manager further providing a userwith the facility to configure the selected individual computerentities, with particular reference to the sizing and dividing of theirnon-volatile data storage devices. Specific implementations according tothe invention herein may be implemented as an alternative or aconventional off-line or near-line back up system, depending upon therequirements of the owner of the computer network.

In one specific embodiment of the present invention, comprising a numberN data storage devices, data from N-1 of the devices can be backed upfrom a remaining one data storage device.

According to a first aspect of the present invention there is provided anetwork of computers comprising:

-   -   a plurality of individual computer devices each having a        non-volatile data storage device and each having means (305) for        communicating with at least one other one of said plurality of        computers;

each said non-volatile data storage device being divided into a firstdata storage area reserved for use by the corresponding computer device,and a second data storage area reserved for backup storage of datacontained in at least one said first data storage area of at least oneother said non-volatile data storage device;

a data protection component for providing data protection for user datastored on each of the non volatile data storage devices by storing theuser data which is resident within the said first data storage area ofeach non volatile data storage device, in one or a plurality of saidsecond data storage areas of other said non volatile data storagedevices.

According to a second aspect of the present invention there is provideda computer entity comprising:

at least one data processor;

at least one non volatile data storage device being divided into a firstdata storage area as a reserve for use by data of said computer entity,and a second data storage area reserved for storage of data contained inat least one other computer entity; and

a data protection component for providing data protection for user dataof said at least one other computer entity.

According to a third aspect of the present invention there is provided amethod of data protection in a network of computer entities comprising aplurality of individual computer entities, each having a data processor,and at least one non-volatile data storage device, and each having meansfor communicating with at least one other of said plurality of computerentities, said method comprising the steps of:

for each said computer entity;

dividing a said non-volatile data storage device of said computer entityinto a first data storage area, and a second data storage area;

assigning said first data storage area for use in storing data for theoperation of a corresponding said respective said data processor; and

assigning said second data storage area for storage of data by at leastone other said computer entity.

According to a fourth aspect of the present invention there is provideda method of data protection in a network of computer entities, each saidcomputer entity comprising at least one data processor and at least onenon-volatile data storage device;

each said non-volatile data storage device being divided into a firstdata storage area dedicated for use by a said corresponding respectivecomputer entity, and a second data storage area dedicated for use instoring data of at least one other one of said plurality of computerentities; said method comprising the steps of:

searching said network of computer entities to find at least onenon-volatile data storage device and selecting individual ones of saidat least one non-volatile data storage devices; and

copying data stored in a first said data storage area of a first saidnon-volatile data storage device into a second said data storage area ofa second said non-volatile data storage device.

According to a fifth aspect of the present invention there is provided amethod of data protection in a computer entity comprising at least onedata processor, at least one non-volatile data storage device, and anetwork port, said data storage device being divided into a first datastorage area dedicated for use by said processor, and a second datastorage area dedicated for use in storing data unrelated to saidprocessor:

said method comprising the steps of:

finding a plurality of other non-volatile data storage devices of othercomputer entities and selecting individual other said non-volatile datastorage devices;

receiving via said network port a said data unrelated to said processor;and

storing said received data in said second data storage area of saidnon-volatile data storage device.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how the same maybe carried into effect, there will now be described by way of exampleonly, specific embodiments, methods and processes according to thepresent invention with reference to the accompanying drawings in which:

FIG. 1 illustrates schematically a prior art network of computerentities including a file server having an off-line data storage device;

FIG. 2 illustrates schematically a plurality of permanently unused datastorage areas of the plurality of computer entities in the prior artnetwork;

FIG. 3 illustrates schematically a network of computer entitiesaccording to a specific implementation of the present invention, inwhich means are provided for utilizing a plurality of unused data areason a plurality of computer entities in the network;

FIG. 4 illustrates schematically an architecture of a data protectionmanager module according to first specific embodiment of the presentinvention;

FIG. 5 illustrates schematically a plurality of non-volatile datastorage devices divided into first and second data storage areasaccording to a specific method of the present invention;

FIG. 6 illustrates schematically a first mode of operation of a computernetwork according to a first specific implementation of the presentinvention;

FIG. 7 illustrates schematically a second mode of operation, being adifferential backup mode, according to the first specific implementationof the present invention;

FIG. 8 illustrates schematically a third mode of operation, being anon-line backup mode of the first specific implementation of the presentinvention;

FIG. 9 illustrates schematically an undivided data storage area of anon-volatile data storage device containing data files distributedthroughout the whole of the data storage area in non-contiguous fashion;

FIG. 10 illustrates schematically a divided data storage area comprisinga first data storage area reserved for use by a processor of a samecomputer entity as the data storage device, and a second data storagearea reserved for use by other computer entities;

FIG. 11 illustrates schematically a method for partitioning a datastorage area of a non-volatile data storage device according to a secondspecific method of the present invention;

FIG. 12 illustrates schematically a set up method for setting up acomputer network to operate a data protection method;

FIG. 13 illustrates schematically a user interface display for findingand selecting computer entities as part of the set up method shown inFIG. 12;

FIG. 14 illustrates schematically a user interface display producedduring the set up method of FIG. 12 herein;

FIG. 15 illustrates schematically a second set up procedure for settingup a second data protection method according to a second specificimplementation of the present invention; and

FIG. 16 illustrates schematically a set up option of the second set upmethod shown in FIG. 15.

DETAILED DESCRIPTION OF THE BEST MODE FOR CARRYING OUT THE INVENTION

There will now be described by way of example the best mode contemplatedby the inventors for carrying out the invention. In the followingdescription numerous specific details are set forth in order to providea thorough understanding of the present invention. It will be apparenthowever, to one skilled in the art, that the present invention may bepracticed without limitation to these specific details. In otherinstances, well known methods and structures have not been described indetail so as not to unnecessarily obscure the present invention.

In this specification, by the term ‘data storage device’, it is meant adata storage device which is seen by a processor to be a single logicaldata storage entity. Examples of data storage devices include: a singlerotating hard disk drive; a raid array comprising a plurality of harddisk drives; a magnetic random access memory device; or the like. Theterm ‘non-volatile data storage device’ shall be interpretedaccordingly.

In this specification, the term ‘computer entity’ refers to at least onedata processor and at least one data storage device operating as asingle logical data processing entity, wherein the at least one datastorage device has a data storage area dedicated for storage of filesused by the processor(s), for their normal operation, and which isinaccessible to other processors outside the computer entity except viathe processor(s) of the computer entity. A single computer entity willusually be contained in its own discrete housing and may be shipped ortransported as a whole unit within its single housing.

Referring to FIG. 1 herein, there is illustrated schematically part of aprior art network of computers comprising a plurality of computers, forexample personal computers 100-102, communicating with each other over alocal area network 104; and a known file server device 105. Each of thenetwork computers 100-102 have a non-volatile hard disk data storagedevice upon which are stored applications and local configurations forthe computer. The file server 105 stores data files which are accessedby the computers, and is provided with a backup facility, for example aknown DDS format tape drive 106. A known approach to data backup is tocopy all data, signified by shaded data areas 203-205 from the harddrive disks of the network computers onto a backup device such as a DDSformat tape device 206 attached to a server, either in an internal bayor on an external connection to that server. Alternatively, oradditionally, data can be backed up onto an on-line data storage systemsuch as the Auto Backup product of Hewlett Packard Company, whichcomprises a plurality of non-volatile hard disk devices.

Referring to FIG. 2 there is shown logically the example prior artcomputer network of FIG. 1 herein. Each conventional computer has anon-volatile hard disk data storage device 200-202 respectfully. Foreach hard disk, a proportion of the disk is likely to remain unused.

Referring to FIG. 3 herein, there is shown schematically a network ofcomputer entities modified to embody and operate according to a specificimplementation of the present invention. Each computer entity comprisesa plurality of application programs 300; an operating system 301; a userinterface 302 including a keyboard, a pointing device such as a mouse ortrackball, and a visual display unit; at least one data processor 303;an amount of memory 304 including volatile memory and a non-volatilememory device, for example a rotating hard disk drive; a communicationsport 305 for communicating with other computers in a network across alocal area network 306; and a data protection management module 307. Acomputer entity may comprise a network attached storage device (NAS),which may not necessarily have attached keyboards, pointing devices andvisual display devices.

It will be understood by these skilled in the art that variations ofprocessor, peripheral device, user interface, operating system andapplications may be present from computer to computer.

The data protection manager module comprises code which is stored in atleast one said non-volatile data storage device. The data protectionmanager module 307 operates to provide data protection for data storedon each of the non-volatile data storage devices, by storing the userdata, which is resident within a first memory area of each non-volatiledata storage devices in one or a plurality of second memory areas ofother non-volatile data storage devices of the plurality of non-volatiledata storage devices.

Referring to FIG. 4 herein, there is illustrated schematically anarchitecture of data protection manager 307. In a preferred embodiment,data protection manager 307 is constructed of a plurality of modules,each module comprising code capable of operating in conjunction with aprocessor and memory means of a computer entity, for performing thespecific methods as described herein. Data protection manager 307comprises a set up module 400 used for setting up a computer entity tooperate data protection according to methods described herein, the setup module 400 comprising a find and select module 401, for finding aplurality of non-volatile data storage devices in a network of computerentities, and enabling a user to select which of the found non-volatiledata storage devices will participate in the data protection methodsdescribed herein; a sizing and dividing module 402 for enabling a userto select a size of first and second data areas within an individualnon-volatile data storage device, and divide the available memory areainto the first and second data storage areas for each said non-volatiledata storage device; a data transfer allocation module 403 forimplementing transfer and copying of data between individualnon-volatile data storage devices, the data transfer allocation module403 comprising a first transfer algorithm 404 capable of operating afully redundant mode of data protection, and a distributed file system(DFS) based algorithm 405 capable of operating a distributed scaleabledata transfer method; a backup scheduler 406 for creating backupschedules and for activating copying of data between first and seconddata areas at preset times; and a user interface generator 407 forgenerating visual displays for scheduling backups, for sizing anddividing data storage areas of data storage devices, and for finding andselecting data storage devices to participate in a data protectionmethod as described herein.

In the best mode implementation, the data protection manager 307 isinstalled on each of a plurality of computer entities in a computernetwork.

There will now be described a first specific method of operation of thenetwork of computer entities of FIG. 3 according to the presentinvention.

Referring to FIG. 5 herein, there is illustrated schematically a logicalrepresentation of a plurality of non-volatile data storage devices502-502, for example rotating hard disk drive units, within acorresponding respective plurality of computer entities 503-505. Afterhaving installed the data protection manager modules 307 onto each of aplurality of computers 503-505, each of the data storage devices 502-502are partitioned into a first storage area 506-508 respectively and asecond data storage area 509-511 respectively. For each computer, data,applications programs, an operating system and all other data andprograms which are necessary for normal operation of a computer areconsolidated to be stored within the first data storage area of thecorresponding respective data storage device. The operating system ofthe computer does not access, for normal operation of that computer, thesecond data storage area of its non-volatile data storage device, butthis is reserved for data protection of user data of at least one otherof the plurality of computers within the network. The first data storageareas 506-508 respectively, may be pre-selectable by the data protectionmanager 307 to reserve a selectable percentage of the overall datacapacity of the data storage device. For example, where a 9 Gbyte driveis installed, one Gbyte of data storage space may be reserved as thefirst data storage area, and the operating system, applications,drivers, and user data for normal operation of the computer may beresident in that first data storage area. The second data storage areamay comprise the remaining 8 Gbytes of available user data space.

For example in a network comprising 9 computers each having a 9 Gbytenon-volatile data storage device, pre-configured such that each datastorage device has a 1 Gbyte first data storage area and an 8 Gbytesecond data storage area, in a robust first mode of operation, each datastorage device contains backup data from the other 8 data storagedevices. That is, where the 9 computers are labeled A-I, the first datastorage area of the data storage device of first computer A containsdata specific to computer A only, and the second data storage area 509of first computer A contains data which is stored in the first datastorage areas of the remaining 8 computers B-I. Thus, the 9 Gbytes ofavailable data storage area on the non-volatile data storage device offirst computer A is occupied by the user data of first computer A,resident in the first data storage area 506, and the computer specificuser data in first data storage areas of each of the other 8 computersB-I is stored in the second data storage area 509 of the first computerA.

Similarly, for second computer B, the first data storage area 507 ofthat computer's data storage device is occupied by data which isspecific to second computer B, whereas the second data storage area 510of the second computer B is occupied by the computer-specific data offirst and third to ninth computers A, C-I. Similarly, for the third toninth computers, each computer stores its own computer specific data, inits own first data storage area, as well as storing the computerspecific data of all the other computers in the network in the seconddata storage area of that computer.

This mode of operation is robust, since the data from all 9 computers inthe network can be recovered from any one computer's data storagedevice. It will be appreciated by those skilled in the art that in afully robust mode of operation, where each computer stores its own dataand the data of all other computers, the number of computers which canparticipate in such a system is limited by the size of the data storagedevice in each computer, and the required amount of computer-specificdata storage area (the first data storage area) which is required.

Within each second data storage area 509-511 the available non volatilestorage area may be pre-partitioned, such that a specific set of memorylocations are reserved for each other computer in the network, so thatother computers in the network which have a low amount of data actuallystored in their first data storage areas will still have available ineach other computer, a partition of size corresponding to the first datastorage area.

Alternatively, the partitioning of the second data storage area of eachdata storage device may be allocated dynamically and filled up byreplication of data in the plurality of first data storage areas of theother computers in the network as and when required.

Referring to FIG. 6 herein, there are illustrated schematically processsteps carried out by data protection manager 307 for data protection ofN selected data storage devices. In step 601, the data manager dividesthe reserved second data storage area into N-1 segments. This may beachieved during a setup procedure in which a user may select which datastorage devices participate in the data protection process. For a numberN participating data storage devices, the data storage manager 307partitions each second data area of each of the N participating datastorage devices into a number N-1 segments. In step 602, for each datastorage device, each of the N-1 segments are assigned to a correspondingrespective first data storage area of each of the other ones of theplurality N of data storage devices participating in the system. In step603, it is checked whether the data protection backup is initiated.Initiation of a data protection backup can be made periodically,according to a backup schedule for each of the N participating datastorage devices independently, or all other the plurality N of datastorage devices can be backed up simultaneously. In step 604, data inthe first data storage area of a first data storage device is copiedonto a corresponding segment on each of the other ones of the pluralityof data storage devices, so that N-1 copies of the data in the firstdata storage area on the first computer are made. Similarly, for second,third and N data storage devices, data in the first data storage area ofthese devices is copied to same data storage areas on each of the N-1other data storage devices. The result is that for each first datastorage area, N-1 copies of the data contained in that first datastorage area are made in the second data storage areas of the N-1 otherdata storage devices.

Referring to FIG. 7 herein, there is illustrated schematically processsteps for a second mode of operation of data protection manager 307.Transfer algorithm 404 operates in a differential backup mode whenactivated by backup scheduler 406. In step 700, set up module 400 isused to set up a plurality of computer entities as illustrated in FIGS.3 and 5 herein as described in steps 600 and 601 previously. In step701, for each data storage device, data files which are resident in thefirst data storage area of that device are copied to a correspondingrespective partition in each of the plurality of N-1 other data storagedevices in the selected group of N data storage devices. Each seconddata storage area has N-1 partitions, each partition assigned to acorresponding respective data storage device other than the data storagedevice on which the partition exists. Either single parity ordistributed parity may be used throughout the plurality of disks in thegroup. The first data storage area is reserved for use of the computerto which that data storage device belongs. In step 702 backup isinitiated via back up scheduler 406, either automatically, or inresponse to a user request. In steps 703 to 707, the transfer algorithm404 in a differential backup mode cycles through each of the plurality Ndata storage devices which have been selected as a backup group by auser via set up module 400. In step 703 data files in the first datastorage area of an N^(TH) data storage device of the group is examined.In step 704, each file in the first data storage area of the NTH datastorage device is compared with a corresponding file in each of theindividual partitions within the second data storage areas of theremaining N-1 data storage devices. If the files in the first datastorage area differ from those stored in the second data storage areasin step 705, then in step 706 the files in the first data storage areawhich are found to have been changed, that is different to those storedin the second data storage areas, are copied to each of the second datastorage areas of the other data storage devices in the group. In step707, the value of N is cycled, that is incremented or decremented, tolook at the next of the N data storage devices in the group. The loop703-707 continues whenever a backup is initiated, or periodically, sothat differential backups of files which have changed since a previousbackup, are copied to the second data storage areas.

Referring to FIG. 8 herein, there is illustrated a third mode ofoperation implemented by the transfer algorithm 404 in the data transferallocation module 403. The third mode comprises an on-line mode of dataprotection. Rather than operating the first or second modes ofoperation, that is the full back up differential backup modes, which areactivated at a specific point in time, the third on-line mode operatessubstantially continuously during operation of a network as a backgroundongoing data protection process. The process shown in FIG. 8 may runindependently on each of a plurality of N computer entities in a group.In step 800, all file system writes occurring to a first data storagearea of the N^(TH) data storage device are examined by the dataprotection manager 307. Whenever a file system write occurs, in steps801 and 802 the write is replicated and sent to each of the partitionscorresponding to the first data storage area of the N^(TH) device, thepartitions being resident in the second data area partitions of allother data storage devices. The steps 800, 801 continue, activated bywrites to the first data storage area until the on-line backup procedureis stopped by a user entering commands through backup scheduler 406. Ina network of computer entities comprising a group of N computer entitiesselected in an on-line backup group, for each computer entity, writes tothe first data storage area of that computer activate sending ofreplicate data writes to all other computer entities for storage in thesecond data storage areas of the other computer entities. Writes may besent across the network substantially simultaneously and independently,by each of the N computer entities in a group.

Referring to FIG. 9 herein, there is illustrated schematically as aseries of lines, data written to a non-volatile data storage device, forexample a rotating hard disk drive. A data storage area 900 comprisingthe whole of the non-volatile data storage device is occupied byindividual files designated as lines 901. Data may be written at logicallocations which are non-contiguous within the data storage area.

As a prerequisite to dividing a data storage device into a first datastorage area reserved for use by a computer to which the data storagedevice forms an integral part, and a second data storage area reservedfor use by other computers in a network, existing data on the device isconsolidated into a set of contiguous addresses within a first data area1001 of the data storage device, as illustrated schematically in FIG. 10herein. The data storage device is divided such that the operatingsystem of the computer having immediate access to the data storagedevice can only utilize the first data storage area 1001 for operationsinvolving data used locally by the computer. Storage of the computer'soperating system, drivers, executable files and local data files is madein first data storage area 1001. A logical division marker 1002 is madesuch that the file system of the computer does not make accessible tonormal use any non volatile data storage locations beyond the divisionmarker 1002. The second data storage area 1003 is reserved for use instoring data of other computers in the network. The data storage managermodule 307 controls access to the second data storage area 1003, byinstructing the processor of the computer to transfer data received fromthe communications port 305 into and out of the second data storage area1003.

Size and divide module 402 operates as illustrated schematically in FIG.11 herein. In step 1100, the module determines the location of thecurrent memory divider 1002, to determine the boundary of the first dataarea. In step 1101, the size and divide module 402 finds data files inthe entire non volatile data storage space 900 of the data storagedevice. In step 1102 the module 402 reads the logical location addressof each file, and determines a size of each file. In step 1103, themodule 402 rewrites the addresses of all the found files, such thatthose files are placed in contiguous blocks in the first data area. Thisleaves the second data area 1003 available for use in storage of data ofother computers. As will be appreciated by those skilled in the art,computer programs for examining non volatile data storage area andrearranging data files in contiguous order are available in the art andmay be incorporated into the data protection manager 307 of the firstembodiment. Data files are moved from their original physical locationson the data storage device to new contiguous blocks of data within thefirst data storage area. The second data area is an unused resource asfar as the computer's operating system is concerned. The second dataarea is not used by the file system of the operating system resident onthe computer.

Referring to FIGS. 12-14, there is illustrated schematically a set upprocedure for selecting a plurality of computer entities to participatein a data protection work group, and for selecting the type of dataprotection and the timing of data protection to run within theworkgroup. In step 1200, a user at any of the computer entities on whichthe data protection manager 307 is installed, having the user interfacegenerator facility 407, may use a display generated on a visual displayunit of the computer's user interface to select individual non-volatiledata storage devices in a computer network. Such a display may include aplurality of icons as illustrated in FIG. 13 showing a number ofcomputers networked together, and displaying icons showing theindividual non-volatile data storage devices which are assigned to thoseindividual computers. In the example of FIG. 13, there are shown 6different computer entities, some of which have more than onenon-volatile data storage device.

In step 1201, the existing capacity of each located non-volatile datastorage device is found.

In steps 1202-1203, set up module 400 is used by a user to find andselect a plurality of individual computer entities having associateddata storage devices, and to define such data storage devices into adata protection group in which data from each of the plurality of datastorage devices in the group is distributed amongst the plurality ofdata storage devices in the group. Existing data files on the datastorage devices are consolidated to contiguous sets in the first datastorage area of the devices in step 1204.

In step 1205, for each data storage device, a second data area isdefined, the second data area being reserved for data specific to otherdata storage devices in the network, comprising other computer entities.Definition of the second storage area size restricts the size of thefirst storage area.

In step 1207, a computer entity can be selected by a user to initiatethe backup procedure. In a data protection group comprising a pluralityof computer entities, one computer entity may be selected to controlbackup of all data storage devices in the group. In step 1208, a type ofdata protection algorithm may be selected for the data storage devicesin a particular group. A particular type of data protection algorithm isassigned to each data storage device in step 1209 following selection instep 1208. As shown schematically in FIG. 14, computers in a network maybe divided into different data protection groups. For example, computershaving drives 1, 2, 3, 6 and 8, where drive 8 is a 20 gigabyte RAIDarray, are included in a same group, operating a distributed file systembased data protection algorithm as herein after described. Computer 4, 5and 7 comprise a second group which may operate according to a fullyredundant mode as described herein with reference to FIG. 6. In step1210, a user may program the backup scheduler using backup schedulemodule 406 via user interface generator 407. It will be appreciated bythose skilled in the art, that prior art code is available forscheduling backups, for example as used in the Hewlett Packard Coloradobackup scheduler. Backup scheduler 406 may comprise a prior art codemodule, adapted to operate within the data protection manager 307.

Whereas the first data protection method and apparatus may operatesatisfactorily for small clusters on computers, or work groups ofcomputers in a larger network, the number of data storage devicesparticipating in the first method and apparatus are limited by the datacapacity of the non-volatile data storage devices and the amount of userdata specific to a particular computer which is stored in a first dataarea. A more scaleable solution is provided by the second dataprotection method described herein, in which data of a plurality offirst data areas is distributed over a plurality of second data areas.

The second data protection method makes use of a distributed file systemalgorithm module 405.

Referring to FIG. 15 herein, there is illustrated schematically a dataprotection scheme based upon a distributed file system. In step 1500, adistributed file system is set up. As will be appreciated by thoseskilled in the art, distributed file systems are known in other priorart environments. A prior art distributed file system algorithm may beincorporated into the DFS based data protection algorithm 405. A groupof computer entities over which the distributed file system dataprotection method will run over is selected similarly as herein beforedescribed using a computer selection displayed as shown in FIG. 13 and adrive selected display as shown in FIG. 14. In step 1501, each selecteddata storage device to participate in a data protection group is dividedinto a first and second data storage area similarly as herein beforedescribed. In the general case, each data storage device must beconfigured into first and second data storage areas independently, sincethe data storage devices may, in practice, be of different capacities toeach other. For example, one data storage device may have a 4 gigabytecapacity and a division of a first data storage area of 1 gigabyte maybe selected and a second data storage area of 3 gigabytes. On the otherhand, a second data storage device of 20 gigabytes capacity may bepartitioned into a 5 gigabyte first data storage area and a 15 gigabytesecond data storage area. Configuration of each non-volatile datastorage device may be made by configuring that particular associatedcomputer entity locally, or, provided permissions are set allowingreconfiguration of the non-volatile data storage device from othercomputer entities, configuration may be made from a single computerentity, selecting each data storage device in the networked system. Instep 1502, each first data storage area is assigned to a correspondingprocessor, and the first data area is reserved for storing dataconcerned with that particular processor. In step 1503, each second datastorage area is assigned to the distributed file system. In step 1504, adegree of redundancy for the data protection scheme is specified by auser, using the displays generated by user interface display generator407. One option for a degree of redundancy to be created in the dataprotection scheme, which may be selected in step 1505, is to operate acommunity of computer entities in a similar manner to which a redundantarray of inexpensive disks (RAID) would be operated. If the dataprotection group comprises a number M computer entities, then data of anM^(th) computer entity is rewritten across a stripe extending across aremaining M-1 computer entities in the group. In one embodiment thesecond data storage space in the M^(th) computer entity, is used forstoring data parity checks. This allows efficient use of the second datastorage areas. In another embodiment, parity may be distributedthroughout the disks. These modes of operation has an advantage overprior art RAID arrays, in that a prior art RAID array may fail as awhole unit (although prior art RAID arrays are themselves made ofindividual component units which are in themselves replaceable).

In the present system, each individual computing entity is discrete, andunlikely to fail, and two computer entities will not fail as a singleunit together. Whilst any individual computer entity or data storagedevice in that entity may fail as a complete unit, it is unlikely thatall computer entities or two computer entities in a group will failsimultaneously. In contrast, a conventional RAID array may have a singlepoint of failure caused by its reliance on a single processor.Similarly, a conventional RAID array is physically present in a singlephysical box. If theft of apparatus occurs, then it is likely that thewhole physical box will be taken. In contrast, in the presentimplementations, individual computer entities are provided in separatediscrete individual boxes. A complete discrete computer entity may beremoved, leaving other computer entities in place, and data recovery maystill be obtained from the remaining computer entities.

Prior art distributed file systems are not intended for use with databackup. However, the functionality of a conventional distributed filesystem may be utilized for distribution of data of one computer entityover a plurality of other computer entities in a data protection group.Configuration of the data protection system depends upon a user'spreference for redundancy. A user may select how a community of computerentities share their data between their non-volatile data storagedevices. A number of concurrent failures of computer entities from whichdata is still recoverable, may be specified by a user by selecting howcomputer entities share data between their data storage devices withinthe data protection group. The network may be expanded by addition of anetwork based non-volatile data storage device, for the purposes ofexpansion and extra data protection.

In step 1506, a user may select a second DFS mode of operation, in whichthe distributed file system is requested to hold at least two copies ofall data at any point in time. For example, in this method, where, forexample there are computer entities A, B, C and D and the data ofcomputer entity A as well as being stored on a first data storage areaof computer entity A is also stored in the second data storage areas ofcomputers B and C, and then computer C is removed from the system, thedistributed file system detects that data from A is now stored only onthe first data partition area of A and the second data partition area ofcomputer B, and therefore creates another copy of the data of A on afourth computer D. In this system, there are forced to be at least twocopies of data made available within the group of computer entities atany one time. Reallocation of data is achieved dynamically under controlof the distributed file system.

Referring to FIG. 16, in step 1506 holding at least two copies of alldata at any point in time may be approached by creating multipledistributed file systems across a plurality of data storage devices in adata protection group in step 1600. This is achieved by creatingmultiple partitions in each second data storage area of each of aplurality of data storage devices in step 1601. The partitions may be ofvarious different sizes, and each partition may contribute independentlyto a different logical distributed file system. Across all computerentities, a first level of DFS may run, followed by a second level ofDFS configured to a different level of redundancy, and subsequent layersof DFS, each configured according to user selected preference todifferent levels of redundancy by assigning individual partitions toindividual ones of a plurality of distributed file systems in step 1602.For example, a first distributed file system may be configured to stripeacross all second data storage areas (step 1505). A second distributedfile system may be configured to back up individual first data storageareas to specified individual second data storage areas (1506).

Once the distributed file systems are set up, in step 1507, backupsoftware is loaded. The backup software provides modes of operationincluding full backup, differential backup, and on-line backups asherein before described with reference to FIGS. 6-8. By virtue of thefact that all the computer entities are contributing to the distributedfile system, any software loaded into the distributed file system isimmediately visible to all computer entities, including the backupsoftware. Therefore, the backup software needs only to be loaded intoone computer entity to be available to all computer entities in thegroup. To improve efficiency of operation of the DFS based dataprotection method, some types of file, for example operating systemfiles which are common to a plurality of computer entities need only bestored in the DFS backup system once, with pointers to individualcomputer entities.

The second method recognizes that distributed file systems can be usedfor data protection, which is a purpose for which they are not designedfor in the prior art to achieve benefits of reduced cost of ownership ofa plurality of computer entities, by reuse of otherwise unusednon-volatile data storage areas and enabling any computer entity withina data protection group selected by a user, which contributes to adistributed file system, to recover their data without having to loadother media, and wait for user initiated commands.

1. A network of computers comprising: a plurality of individual computerdevices each having a non-volatile data storage device, and each of thecomputer devices being arranged for communicating with at least oneother one of said plurality of computers; each said non-volatile datastorage device being divided into a first data storage area reserved forfiles to be used by the at least one processor of the correspondingcomputer device for its normal operation and which is inaccessible toother processors outside the individual computer device except via theat least one processor of the computer entity, and a second data storagearea reserved for backup storage of data included in at least one saidfirst data storage area of at least one other said non-volatile datastorage device; a data protection component for providing dataprotection for user data stored on each of the non volatile data storagedevices by storing the user data which is resident within the said firstdata storage area of each non volatile data storage device, in one or aplurality of said second data storage areas of other said non volatiledata storage devices.
 2. The network of computers as claimed in claim 1,comprising a set-up component for defining said data storage devicesinto a data protection group in which data from each of the plurality ofdata storage devices in the group are distributed amongst the pluralityof data storage devices in the group.
 3. The network of computers asclaimed in claim 1, comprising: a sizer configured for selecting a sizeof a first and a second data storage area of each of said plurality ofnon-volatile data storage devices.
 4. The network of computers asclaimed in claim 1, further comprising a finder for finding a pluralityof non volatile data storage devices.
 5. The network of computers asclaimed in claim 1, further comprising; a selector for selectingindividual ones of said plurality of non volatile data storage devices.6. The network of computers as claimed in claim 1, comprising: ascheduler for scheduling copying of data between individual ones of saidplurality of non-volatile data storage devices.
 7. The network ofcomputers as claimed in claim 1, comprising: a mode selector forselecting between a distributed mode of data copying, in which data ofeach of a plurality of said first data areas is adapted to be copied toa plurality of said second data areas, and a redundant mode in whichdata of each said first data storage area is adapted to be copied tosaid second data storage areas of all of the other ones of plurality ofnon-volatile data storage devices.
 8. A computer entity comprising: atleast one data processor; at least one non volatile data storage devicebeing divided into a first data storage area as a reserve for files tobe used by data of said computer entity, and a second data storage areareserved for storage of data included in at least one other computerentity; and a data protection component for providing data protectionfor user data of said at least one other computer entity.
 9. Thecomputer entity as claimed in claim 8, further comprising: at least onenetwork port; a data transferor component for sending a copy of saiddata stored in said first data storage area to said network ports. 10.The computer entity as claimed in claim 8, further comprising: a findercomponent for finding at least one other non volatile data storagedevice.
 11. The computer entity as claimed in claim 10, furthercomprising: a selector component for selecting at least one individualone of a plurality of unrelated non volatile data storage devices. 12.The computer entity as claimed in claim 10, wherein said data storagedevice is arranged for causing said second data storage area to storedata relating to a plurality of other computing entities in stripeddistributed format.
 13. The computer entity as claimed in claim 10,wherein said data storage device is arranged for causing said seconddata storage area to store, in a plurality of partitions, a plurality ofindividual blocks of data each relating to a corresponding respectiveother computer entity such that data of each said other computing entityis stored in a corresponding respective one of said partitions.
 14. Amethod of data protection in a network of computer entities comprising aplurality of individual computer entities, each having a data processor,and at least one non-volatile data storage device, and each of thecomputer entities being arranged for communicating with at least oneother of said plurality of computer entities, said method comprising,for each said computer entity, the steps of: dividing a saidnon-volatile data storage device of said computer entity into a firstdata storage area, and a second data storage area; assigning said firstdata storage area for use in storing data for the operation of acorresponding said respective said data processor; and assigning saidsecond data storage area for storage of data by at least one other saidcomputer entity.
 15. The method as claimed in claim 14, furthercomprising, for each said second data storage area, the step of:partitioning said second data storage area into a plurality ofpartitions; and assigning each said partition for storing data specificto a corresponding respective other one of said plurality of computerentities.
 16. A method of data protection in a network of computerentities, each said computer entity comprising at least one dataprocessor and at least one non-volatile data storage device, each saidnon-volatile data storage device being divided into a first data storagearea dedicated for use by a said corresponding respective computerentity, and a second data storage area dedicated for use in storing dataof at least one other one of said plurality of computer entities, saidmethod comprising the steps of: searching said network of computerentities to find at least one non-volatile data storage device andselecting individual ones of said at least one non-volatile data storagedevices; and copying data stored in a first said data storage area of afirst said non-volatile data storage device into a second said datastorage area of a second said non-volatile data storage device.
 17. Themethod as claimed in claim 16, wherein each said second data storagearea is arranged into a plurality of partition areas, and each partitionarea of an individual said second data storage area is assigned to storedata of a corresponding respective other said data storage device. 18.The method as claimed in claim 16, wherein, for each of said pluralityof computer entities: data stored in a said first data storage area ofsaid at least one data storage device of said computer is replicated andstored in a plurality of second data storage areas of a plurality ofother said computer entities within said network.
 19. The method asclaimed in claim 16, wherein: each said computer entity writes a writedata to its corresponding said at least one data storage device; upon asaid computer entity writing a said write data, said computer entitysends a copy of said write data to at least one other computer entity ofsaid plurality of computer entities in said network; and said at leastone other computer entity stores said write data in a second datastorage area of a said data storage device of said other computerentity.
 20. The method as claimed in claim 16, wherein: data stored in afirst said data storage area of a first computer entity is stored as astripe in a plurality of said second data storage areas of a pluralityof other ones of said computer entities comprising said network.
 21. Amethod of data protection in a computer entity comprising at least onedata processor, at least one non-volatile data storage device, and anetwork port, said data storage device being divided into a first datastorage area dedicated for files used by said at least one processor forits normal operation and which is inaccessible to other processorsoutside the individual computer entity except via the at least oneprocessor of the computer entity, and a second data storage areadedicated for use in storing data unrelated to said processor, saidmethod comprising the steps of: finding a plurality of othernon-volatile data storage devices of other computer entities andselecting individual other said non-volatile data storage devices;receiving via said network port a said data unrelated to said processor;and storing said received data in said second data storage area of saidnon-volatile data storage device.
 22. The method as claimed in claim 21,wherein: said received data comprises data of a plurality of differentother computer entities; said second data storage area is arranged intoa plurality of different partitions; and said step of storing saidreceived data comprises: storing received data of each of said othercomputer entities in a corresponding respective said partition.
 23. Themethod as claimed in claim 21, wherein: said received data comprisesincremental backup data of at least one other computer entity, saidincremental backup data comprising files which have been rewritten to bedifferent on said first data storage area compared to at least onecorresponding file in a said second data storage area.
 24. The method asclaimed in claim 21, wherein said received data comprises a write datasent by at least one other computer entity in response to a plurality ofwrite events occurring locally on said other computer entity.